Université de Fribourg

Hypothesis test of the photon count distribution for dust discrimination in dynamic light scattering

Bossert, David ; Crippa, Federica ; Petri-Fink, Alke ; Balog, Sandor

In: Analytical Chemistry, 2018, vol. 90, no. 6, p. 3656–3660

Users of dynamic light scattering (DLS) are challenged when a sample of nanoparticles (NPs) contains dust. This is a frequently inevitable scenario and a major problem that critically affects the reproducibility and accuracy of DLS measurements. Current methods approach this problem via photon correlation spectroscopy, but remedy exists only for a few special cases. We introduce here a...

Université de Fribourg

Structural behavior of cylindrical polystyrene-block-poly(ethylene-butylene)-block-polystyrene (SEBS) triblock copolymer containing MWCNTs: on the influence of nanoparticle surface modification

Hasanabadi, Noushin ; Nazockdast, Hossein ; Gajewska, Bernadetta ; Balog, Sandor ; Gunkel, Ilja ; Bruns, Nico ; Lattuada, Marco

In: Macromolecular Chemistry and Physics, 2017/218/22/n/a-n/a

In this work, the influence of carbon nanotubes (CNTs) on the self-assembly of nanocomposite materials made of cylinder-forming polystyrene-block-poly(ethylene- butylene)-block-polystyrene (SEBS) is studied. CNTs are modified with polystyrene (PS) brushes by surface-initiated atom transfer radical polymerization to facilitate both their dispersion and the orientation of neighboring PS domains...

Université de Fribourg

Rheological characterization of nanostructured material based on Polystyrene-b-poly(ethylene-butylene)-b-polystyrene (SEBS) block copolymer: Effect of block copolymer composition and nanoparticle geometry

Hasanabadi, Noushin ; Nazockdast, Hossein ; Balog, Sandor ; Lattuada, Marco

In: Composites Science and Technology, 2017, vol. 149, no. Supplement C, p. 192–206

Block copolymer (BCP) nanocomposite systems are of broad interest; however, reports on the role of nanoparticles on microphase separation behavior are rare. The goal of present study is to investigate the preparation of composite nanostructured materials containing Multi-Walled Carbon Nanotubes (MWCNTs) or graphene nanoplates. BCP nanocomposites based on the linear triblock copolymer, ...

Université de Fribourg

Light-responsive azo-containing organogels

Ayer, Mathieu A. ; Schrettl , Stephen ; Balog, Sandor ; Simon, Yoan C. ; Weder, Christoph

In: Soft Matter, 2017, vol. 13, no. 22, p. 4017-4023

While azo compounds are widely employed as radical initiators, they have rarely been used as stimuli-responsive motifs in macromolecular constructs. In this study, an azo-based cross-linker was prepared and reacted with poly(vinyl alcohol) to afford a series of stimuli-responsive organogels. Irradiation of these materials with UV light causes de-cross-linking and triggers a solid-to-liquid phase...

Université de Fribourg

Vesicle origami: cuboid phospholipid vesicles formed by template‐free self‐assembly

Neuhaus, Frederik ; Mueller, Dennis ; Tanasescu, Radu ; Balog, Sandor ; Ishikawa, Takashi ; Brezesinski, Gerald ; Zumbuehl,  Andreas

In: Angewandte Chemie International Edition, 2017, vol. 56, no. 23, p. 6515–6518

Phospholipid liposomes are archetypical self-assembled structures. To minimize the surface tension, the vesicles typically are spherical. Deciphering the bilayer code, the basic physical interactions between phospholipids would allow these molecules to be utilized as building blocks for novel, non-spherical structures. A 1,2- diamidophospholipid is presented that self-assembles into a cuboid...

Université de Fribourg

A new angle on dynamic depolarized light scattering: number-averaged size distribution of nanoparticles in focus

Geers, Christoph ; Rodriguez-Lorenzo, Laura ; Urban, Dominic Andreas ; Kinnear, Calum ; Petri-Fink, Alke ; Balog, Sandor

In: Nanoscale, 2016, vol. 8, no. 34, p. 15813–15821

Size polydispersity is a common phenomenon that strongly influences the physicochemical properties of nanoparticles (NPs). We present an analytical approach that is universally applicable to characterizing optically anisotropic round NPs and determines directly the number-averaged size distribution and polydispersity via depolarized dynamic light scattering (DDLS). To demonstrate, we use...

Université de Fribourg

Synthesis of poly(sulfonate ester)s by ADMET polymerization

Parkhurst, Rebecca R. ; Balog, Sandor ; Weder, Christoph ; Simon, Yoan C.

In: RSC Advances, 2014, vol. 4, p. 53967-53974

Many hydrocarbon polymers containing heteroatom defects in the main chain have been investigated as degradable polyethylene-like materials, including aliphatic polyesters. Here, acyclic diene metathesis (ADMET) polymerization was used for the synthesis of aliphatic poly(sulfonate ester)s. The requisite sulfonate ester containing α,ω-diene monomers with varying numbers of methylene groups...

Université de Fribourg

Mechanochemistry with Metallosupramolecular Polymers

Balkenende, Diederik W. R. ; Coulibaly, Souleymane ; Balog, Sandor ; Simon, Yoan C. ; Fiore, Gina L. ; Weder, Christoph

In: Journal of the American Chemical Society, 2014, vol. 136, no. 29, p. 10493-10498

The transduction of mechanical force into useful chemical reactions is an emerging design approach to impart soft materials with new functions. Here, we report that mechanochemical transductions can be achieved in metallo-supramolecular polymers. We show that both reversible and irreversible reactions are possible and useful to create me-chanically responsive materials that display new...